This invention relates to the field of powdered metallurgy, and more particularly, to the preparation of samples of powdered metals for oxygen analysis.
In the field of powdered metallurgy, it is often necessary to provide a sample of a powdered metal for oxygen analysis to determine the oxygen content therein. This analysis is accomplished by heating a sample of the powdered metal, for example titanium or tungsten, in a crucible and taking a background reading of the oxygen content in the crucible. A standard reference for oxygen analysis acceptability is approximately 600 to 1300 parts per million.
A typical procedure for the preparation of a powdered metal sample for oxygen analysis is to encapsulate a measured amount of the powder in a tin foil packet. In that powdered metals tend to oxidize, the encapsulation procedure must be done in an inert atmosphere such as argon. To achieve the inert atmosphere, the sample is typically collected and packaged in the tin foil in a glove box. The glove box includes a pair of gloves, typically rubberized and often bulky, which the operator uses to encapsulate the sample in the foil within the glove box.
The samples deposited into the crucible of the analyzer for oxygen analysis should ideally be well formed and of a uniform size in order to yield consistently accurate results. Typically, a 0.2 gram sample of the powdered metal is required for the oxygen analysis. Due to the nature of the gloves and the small scale of the samples, the operator usually has an extremely difficult time handling the foil and powdered metal within the glove box, The bulky gloves detrimentally affect the manual dexterity of the operator. As a result, powdered metal samples for oxygen analysis which are packaged in the glove box are often of varying sizes and shapes.
In addition to the problem of non-uniformity of package sizes prepared in a glove box, the tin foil sheet used to encapsulate the sample is typically very thin, approximately 0.0005 of an inch thick. Therefore, the foil easily tears and the packages prepared in the glove box are easily damaged allowing the powdered metal to leak from the package, thereby resulting in a non-uniform sample weight and inconsistent test results.
These and other difficulties encountered in handling and manipulating very small samples of powdered metal while operating in a glove box result in a very tedious and time consuming process for the operator. Numerous samples are often required for repeated analysis. A typical preparation time for a powdered metal sample in a glove box is approximately one minute. However, even a careful and diligent operator can expect as much as an 80% rejection rate of samples prepared in a glove box due to irregularly sized, shaped, damaged and/or leaking sample packets.